Mesoscale eddies and Trichodesmium spp. distributions in the southwestern North Atlantic

• Published in: Journal of geophysical research. Oceans Vol. 120; no. 6; pp. 4129 - 4150
• Main Authors: Olson, Elise M., McGillicuddy, Dennis J., Flierl, Glenn R., Davis, Cabell S., Dyhrman, Sonya T., Waterbury, John B.
• Format: Journal Article
• Language: English
• Published: 01.06.2015
• Subjects: Amazon plume; eddy‐wind interaction; video plankton recorder
• ISSN: 2169-9275; 2169-9291
• DOI: 10.1002/2015JC010728

Correlations of Trichodesmium colony abundance with the eddy field emerged in two segments of Video Plankton Recorder observations made in the southwestern North Atlantic during fall 2010 and spring 2011. In fall 2010, local maxima in abundance were observed in cyclones. We hypothesized surface Ekman transport convergence as a mechanism for trapping buoyant colonies in cyclones. Idealized models supported the potential of this process to influence the distribution of buoyant colonies over time scales of several months. In spring 2011, the highest vertically integrated colony abundances were observed in anticyclones. These peaks in abundance correlated with anomalously fresh water, suggesting riverine input as a driver of the relationship. These contrasting results in cyclones and anticyclones highlight distinct mechanisms by which mesoscale eddies can influence the abundance and distribution of Trichodesmium populations of the southwestern North Atlantic. Key Points: Trichodesmium abundance was elevated in certain cyclonic and anticyclonic eddies Enhancement in cyclonic eddies could be driven by Ekman convergence Anticyclonic eddies with elevated abundance were anomalously fresh